The invention relates to a television transmission system for the simultaneous transmission of television signals from the same scene for standard and wide picture formats of, respectively, a standard aspect ratio and a wider than standard aspect ratio with both picture formats having the same height, in which a wide band television signal, which represents the full width of the wide picture format, having n lines per picture is converted into a narrower band television signal, also representing the full width of the wide picture format, having m lines per picture where m is substantially 1/2n with both signals having the same field and picture rates, respective adjacent lines of a field of said converted television signal being derived from respective alternate lines in a field of said wide band signal. The invention also relates to television transmission and reception equipment for use with such a system.
Television signals in most countries of the world are transmitted in such a manner that they can be correctly displayed on a display system having a picture format with a standard aspect ratio of 4:3 where the picture width is greater than the height. Much discussion has taken place in recent years on the subject of the possible transmission of television signals where the picture format is of greater width than at present and one proposal has been to employ an aspect ratio of 5:3. Some experimental work has already taken place in Japan using a picture format with as aspect ratio of 5:3 with a line standard above that for standard transmission (625 lines). However, such work has led to signals which have to use a display format of 5:3 aspect ratio and which are not compatible with standard transmissions and cannot be received by television receivers designed to reproduce standard television transmissions.